Power generation devices, such as solar or wind power generation devices, are devices designed to generate power. A photovoltaic device generates power by transforming solar energy into electricity and supplies the power to a home as a natural source of energy. The amount of power generated by a photovoltaic device constantly fluctuates with weather and meteorological conditions.
A heat pump hot water supply device heats a refrigerant by absorbing heat from the atmosphere and compressing the refrigerant using electricity. The heat is then transferred to the water via a heat exchanger, creating hot water. The heat pump hot water supply device uses less energy than a conventional electric hot water heater.
A heat pump hot water supply system including a power generation device includes a combination of the above devices, and supplies a consumer with power and heat. An example of this type of conventional heat pump hot water supply system including a power generation device is disclosed in Patent Literature (PTL) 1.
PTL 1 discloses a heat pump hot water supply system which obtains weather forecast information from a server using a weather information obtaining unit. When the obtained information meets a predetermined condition, the heat pump hot water supply system switches to use photovoltaic power to heat the water in the CO2 heat pump hot water supply device instead of late night power from a commercial power source. Operating using power harnessed from natural energy allows for a power efficient, low-energy electric heat pump hot water supply device which can reduce electricity costs.